Can we make that a PO is rejected when the RQ creator is the same person as the PO approver?

Summary:

 We had cases in PROD where the creator of the RQ selects a requester (different than RQ creator) that triggers a flow on the PO that goes to the same person (RQ creator) for approval once created and submitted.

We consider this as not acceptable and we don't have a system control at the moment to prevent it.

Content (please ensure you mask any confidential information):

In our company, Requisitions are auto approved and we are using BPM approvals for Purchase Orders:

• We use position hierarchy 
• Terms Approval Stage
•  Method: Serial. 
• Position Chain Of: Requester Position
• Start With: Next Position